Enhanced peroxymonosulfate-mediated photocatalytic pesticide degradation by a novel stable multi-metal ferrite (Mg, Cu, Fe) anchored on g-C3N4

Abstract

In this study, an innovative assembly of multi-metal ferrite nanoparticles, MgCuFe₂O₄ (MCF), was anchored on a g-C₃N₄ (GCN) surface to improve the degradation efficiency of 2,4-dichlorophenoxyacetic acid (2,4-D) over a visible-light (VL)-assisted peroxymonosulfate (PMS) activation system. Optimal characterization revealed a distinct enhancement in the photocatalytic activity of GCN after the introduction of MCF owing to the rapid transfer of photo-induced charge carriers. An extensive spectrum of radical and non-radical agents was identified in the GCN@MCF/PMS/VL system, which played a pivotal role in the effective degradation of 2,4-D. Based on the reaction rate constants of the first-order kinetics, a strong synergistic effect was attained for the integrated GCN@MCF/PMS/VL system to degrade 2,4-D. More than 98.5% of 2,4-D (5.0 mg L⁻¹) and 60% of the TOC were removed within 120 min at pH 6.5, 5.0 mM PMS, and 0.3 g L⁻¹ catalyst. Recycling tests revealed that the degradation efficiency remained the same even after six successive runs. A comprehensive degradation pathway was proposed based on the intermediates and quenching tests. According to trapping tests, HO˙, h⁺, SO₄˙⁻, O₂˙⁻, and ¹O₂ contributed to the photocatalytic degradation of 2,4-D. The degradation mechanism showed that 2,4-D degraded to 2,4-DCP, 2-CHQ, HQ, 2-C-1,4-BQ, and aliphatic acids at the end. Biodegradability indices confirmed the biodegradable nature of the effluent obtained from the GCN@MCF/PMS/VL system. In conclusion, the integration of the GCN@MCF-mediated PMS activation system may offer significant benefits for the effective decontamination of pesticide-contaminated water.